Sustainable utilization of incineration bottom ash in pavement construction: Environmental impacts and life cycle assessment

The global drive towards sustainable development has prompted a notable shift in civil engineering practices towards utilizing secondary materials, such as incineration bottom ash (IBA). The literature review underscores the relevance of waste incineration and the crucial need for effective IBA management strategies. Existing studies, however, reveal a dearth of studies within the life cycle assessment (LCA) framework focusing on understanding IBA characteristics and field conditions. The study addresses this gap by proposing an LCA to assess the environmental implications of substituting natural aggregates with IBA in pavement layers. A comparative LCA was carried out, where different scenarios of reuse of IBA (as produced, treated, or with restrictions) were assessed against a baseline scenario that represents the conventional use of aggregates in roads and landfilling of IBA. The ReCiPe technique, incorporating a hierarchist perspective, was employed to assess impacts across different problem-oriented categories. Additionally, this study also explores the impact of data variability on LCA outcomes, considering changes in landfill height, pavement infiltration rate, time duration, and IBA transportation distance. The analysis indicates that incorporating IBA in road layers can significantly reduce impacts on non-toxic categories like global warming by over 35 %. However, the leaching properties of untreated IBA contribute to a more than 28 % increase in human carcinogenic toxicity, rendering it environmentally unsuitable for road layer reuse. The comparative study illustrated that reusing treated IBA is the most sustainable approach, remaining effective up to a distance of d + 15 km. In cases where treatment is not feasible, utilizing IBA with restrictions is recommended up to a distance of d + 5 km (d represents the transportation distance for natural materials). This research fills a critical gap in the literature by providing a framework to assess IBA reuse in road construction, thereby advancing the discourse on sustainable materials management in the construction industry.